<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <title>隐藏域示例</title>
</head>

<body>

    <form action="/submit_form" method="post">
        <p>用户信息：</p>

        <!-- 普通文本输入框 -->
        <label for="username">用户名：</label>
        <input type="text" id="username" name="username">

        <!-- 密码输入框 -->
        <label for="password">密码：</label>
        <input type="password" id="password" name="password">

        <!-- 隐藏域 -->
        <input type="hidden" name="user_id" value="123456">

        <p><input type="submit" value="提交"></p>

    </form>

</body>

</html>